Semiconductor element and manufacturing method thereof

ABSTRACT

In a semiconductor element, if a crack is generated inside a bonding pad, the crack does not propagate inside the semiconductor element. The semiconductor element has an electrode on a surface thereof. A wiring layer is formed inside the semiconductor element. A conductive layer is formed separate from the wiring layer so as to form a surface of the electrode. A plurality of pole-like members are formed of a conductive material and extending between the wiring layer and the conductive layer and arranged adjacent to each other. The insulating layer is formed of an insulating material filled between the plurality of pole-like members. A frame member extends between the wiring layer and the conductive layer so as to surround the plurality of pole-like members and the insulating layer together.

This application is a divisional of Ser. No. 11/208,549, filed Aug. 23,2005, which is based upon and claims the benefit of priority from priorJapanese Patent Application No. 2005-157538, filed May 30, 2005, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a semiconductor element and amanufacturing method thereof and, more particularly, to a semiconductorelement having a bonding par or a bump pad or a probing pad that servesas a connection terminal of the semiconductor element in a semiconductordevice and a manufacturing method of such a semiconductor element.

2. Description of the Related Art

Generally, a semiconductor element incorporated in a semiconductordevice is provided with a plurality of electrodes for acquiring anelectric contact with an external device. For example, if the electrodesserve as connection pads of bonding wires, those electrodes are referredto as bonding pads. If the electrodes serve as connection pads of bumps,those electrodes are referred to as bump pads. Additionally, if theelectrodes serve aw connection pads for contacting with probe needles,those electrodes are referred to as probing pads. Hereinafter, thebonding pads are explained below as a representative of the bondingpads, the bump pads and the probing pads.

FIG. 1 is a perspective view showing a part of an integrated circuitpackage (semiconductor device) in which a semiconductor element having aplurality of bonding pads are incorporated. As shown in FIG. 1, thebonding pads 6 a of the semiconductor element 6 mounted on a die stage 4of a lead frame 2 within the semiconductor device are connected to innerleads 2 a of the lead frame 2 by bonding wires 8.

FIG. 2 is a plan view of the bonding pads shown in FIG. 1. FIG. 3 is across-sectional view taken along a line III-III in FIG. 2.

As shown in FIG. 2 and FIG. 3, generally, the bonding pads 6 a formed inthe semiconductor element have a structure in which many conductiveplugs 16, which are made of tungsten or the like and arranged in amatrix pattern, are formed on a lower wiring layer 14 made of aluminumor the like, and an upper conductive layer 18 made of aluminum or thelike is formed on the conductive plugs 16. Between the lower wiringlayer 14 and the upper conductive layer 18, an insulating layer 20 isformed around the conductive plug 16.

It should be noted that the lower wiring layer 14 is formed on aninterlayer insulating film 12 formed on a semiconductor substrate 10,and serves as an internal wiring of the semiconductor element.Additionally, an outer circumferential portion of the upper conductivelayer 18 is covered by a cover film 22, and the upper conductive layer18 is exposed in openings formed in the cover film 22.

Here, in a process of forming the semiconductor element, for example, anelectric characteristic test is performed by performing an electric testso as to determine whether or not the semiconductor device is good ordefective. In this case, is it necessary to bring test probe pins intocontact with the bonding pads 6 a (upper conductive layer 18). When thetest probe pins are pressed onto the upper conductive layer 18, a stressis concentrated into the insulating layer, which is hard and brittle ascompared to the upper aluminum layer and the conductive plugs 16. Due tothe stress concentration, there may be a case in which a crack isgenerated in the insulating layer 20 between the conductive plugs 16.

Such a crack does not propagate to the conductive plug 16, and ends whenthe crack reaches the conductive plug 16. However, the conductive plugs16 are arranged in a matrix pattern, and in the cross-section shown inFIG. 4, the crack may propagate within the insulating layer 20 withoutrunning into the conductive plugs 16.

Moreover, a flaw may be formed on the upper conductive layer 18 by thetest probe pins being pressed onto the upper conductive layer 18. Such aflaw may propagate within the insulating layer 20. Then, if a watercomponent enters the flaw, the water component enters inside thesemiconductor element, which may cause a moisture resistance defect.

Thus, in order to solve the above-mentioned problem, there is suggesteda bonding pad having a structure in which the conductive plugs and theportions of the insulating layer are exchanged so as to make a grid-likeconductive portion 16A and island-like insulating layer 20 as shown inFIG. 5 and FIG. 6 (for example, refer to Patent Document 1). It shouldbe noted that FIG. 5 is a plane view of the bonding pad 6Aa having thegrid-like conductive portion 16A, and FIG. 6 is a cross-sectional viewtaken along a line VI-VI of FIG. 5.

That is, between the upper conductive layer 18 and the lower wiringlayer 14, the grid-like conductive portion 16A corresponding to theconductive plugs is formed of tungsten or the like, and an insulatingmaterial is filled in each square portion within the grid-likeconductive portion 16A so as to form the insulating layer 20. Accordingto such a structure, the insulating layer 20, which tends to generate acrack, is surrounded by wall surfaces of the grid-like conductiveportion 16A. Accordingly, is a crack is generated in the insulatinglayer 20 corresponding to one square portion, the crack does notpropagate to the insulating layer 20 of other square portions or theinsulating layer 20 outside the grid-like conductive portion 16A.

The following documents relate to the above-mentioned background art ofthe present invention.

Patent Document 1: Japanese Laid-Open Patent Application No. 2002-208610

Patent Document 2: Japanese Laid-Open Patent Application No. 10-64945

The above-mentioned grid-like conductive portion 16A can be formed byforming portions corresponding to openings of the grid pattern (that is,the island-like insulating layer 20) and filling tungsten or the likebetween the island-like insulating layer 20. However, since theinsulating material forming the insulating layer 20 has a pole shape, acontact area with the lower wiring layer 14 is small. Thus, there may bea problem in that the pole-like insulating layer 20 separate and falloff from the lower wiring layer 14 as shown in FIG. 7 when performingetching, ashing, post processing, cleaning, and drying in the formingprocess of the insulating layer 20 or when performing cleaning or dryingin a subsequent process. It should be noted that, in FIG. 7, the islandlike insulating layer 20 is indicated not as a square pole but acylindrical pole. Although the island-like insulating layer 20 isindicated as a square pole in FIG. 4 and FIG. 5, it may be a shape closeto cylindrical pole when forming in practice.

In addition, the may happen a problem in that the conductive materialcannot be properly filled in a portion indicated by a reference numeral38 in FIG. 8 or a recess is formed when filling the conductive materialsuch as tungsten or the like around the island-like insulating layer 20,which cannot acquire a good coverage. It should be noted that theisland-like insulating layer 20 is indicated as a cylindrical pole alsoin FIG. 8.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide an improvedand useful semiconductor element and manufacturing method thereof inwhich the above-mentioned problems are eliminated.

A more specific object of the present invention is to provide asemiconductor element having a structure in which, if a crack isgenerated inside a bonding pad, the crack does not propagate inside thesemiconductor element.

In order to achieve the above-mentioned objects, there is providedaccording to one aspect of the present invention a semiconductor elementhaving an electrode on a surface thereof, the semiconductor elementcomprising: a wiring layer formed inside the semiconductor element; aconductive layer formed separate from the wiring layer so as to form asurface of the electrode; a plurality of pole-like members formed of aconductive material and extending between the wiring layer and theconductive layer and arranged adjacent to each other; an insulatinglayer formed of an insulating material filled between the plurality ofpole-like members; and a frame member extending between the wiring layerand the conductive layer so as to surround the plurality of pole-likemembers and the insulating layer together.

Additionally, there is provided according to another aspect of thepresent invention a manufacturing method of a semiconductor elementhaving an electrode on a surface thereof, the manufacturing methodcomprising: forming a plurality of pole-like members and a frame memberon a wiring layer inside the semiconductor element so that the framemember surrounds the plurality of pole-like members; forming aninsulating layer by filling an insulating material between the pole-likemembers; and forming a conductive layer on the plurality of pole-likemembers, the insulating member and the frame member so as to make asurface of the conductive layer as a surface of the electrode. The framemember may be formed by the same material as the pole-like members.

According to the present invention, even if a crack is generated in theinsulating layer under the electrode due to a stress applied onto theelectrode when being contacted by a test probe pin, performingwire-bonding or forming a bump, propagation of the crack is prevented bythe frame member and the crack does not propagate inside thesemiconductor element. Accordingly, generation of a moisture resistancedefect due to a water component entering inside the semiconductorelement is prevented. Additionally, since the insulating layer in theelectrode structure is in a continuous form connected with each other, aportion of the insulating layer cannot fall off in the manufacturingprocess.

Additionally, according to the present invention, the pole-like membersare not only surrounded by the frame member but also completelysurrounded in vertical directions and horizontal directions togetherwith the insulating layer by the wiring layer, the intermediateconductive layer, the conductive layer and the frame member. Thus, evenif a crack propagates in vertical directions, the crack cannot propagateoutside the bonding pad structure, and the crack is confined within thebonding pad structure.

Other objects features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a part of an integrated circuit packagein which a semiconductor element having a plurality of bonding pads areincorporated;

FIG. 2 is a plan view of the bonding pads shown in FIG. 1;

FIG. 3 is a cross-sectional view taken along a line III-III in FIG. 2;

FIG. 4 is a cross-sectional view taken along a line IV-IV of FIG. 2;

FIG. 5 is a plane view of a bonding pad having a grid-like conductiveportion:

FIG. 6 is a cross-sectional view taken along a line VI-VI of FIG. 5;

FIG. 7 is an illustration showing a state of an insulating layer shownin FIG. 5;

FIG. 8 is an illustration showing a art of a grid-like member shown inFIG. 5;

FIG. 9 is a plan view of a bonding pad of a semiconductor elementaccording to an embodiment of the present invention;

FIG. 10 is a cross-sectional view taken along a line X-X of FIG. 9; and

FIG. 11 is a cross-sectional view taken along a line XI-XI of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given, with reference to the drawings, of anembodiment according to the present invention.

FIG. 9 is a plan view of a bonding pad portion according to anembodiment of the present invention. FIG. 10 is a cross-sectional viewtaken along a line X-X of FIG. 9. FIG. 11 is a cross-sectional viewtaken along a XI-XI of FIG. 9. In FIGS. 9 through 11, parts that are thesame as the parts shown in FIG. 2 and FIG. 3 are given the samereference numerals.

In the present embodiment, a bonding pad 40 has a two-stage structure,and as shown in FIG. 10, an intermediate conductive layer 42 is providedbetween upper and lower conductive plugs 16. The conductive plugs arepole-like members formed of a conductive material. In the presentembodiment, the upper conductive layer 18 and the intermediateconductive layer 42 are electrically connected to each other by theupper conductive plugs 16, which are pole-like members formed by aconductive material such as tungsten or the like. Similarly, theintermediate conductive layer 42 and the lower wiring layer 14 areelectrically connected to each other by the lower conductive plugs 16,which are pole-like members formed by a conductive material such astungsten or the like. An externally exposed surface of the upperconductive layer 18 serves as a bonding surface to which a bonding wire8 is joined.

Although the bonding pad 40 is configured to be the two-stage structureas mentioned above in the present embodiment, the bonding pad may have asingle-stage structure or a multi-stage structure having more than 3stages. A number of stages of the bonding pad can be determined inaccordance with a distance between the upper conductive layer 18 and theinterlayer insulating film 12 formed on the semiconductor substrate 10.

In the present embodiment, as shown in FIG. 9, an outermostcircumferential portion of the conductive plugs 16 positioned arrangedin a matrix form is configured as a frame member 44, which is continuousover an entire circumference. In the present embodiment, the framemember 44 is formed of the same material as the conductive plugs 16,such as tungsten or the like, and, thereby, the frame member 40 can beformed in the same process of forming the tungsten plugs 16.Accordingly, similar to the conductive plugs 16, the frame member 44also serves as a member that electrically connects the lower wiringlayer 14 and the upper conductive layer with each other.

It should be noted that it is preferable to use tungsten (W), copper(Cu), aluminum (Al) or the like as a conductive material to form theconductive plugs 16 and the frame member 44. Additionally, as aninsulating material to form an insulating layer 20, there are siliconoxide (SixOy), NSG, Silk, a low-dielectric-constant material (low-k)material, etc.

A width of the frame member 44 is preferably set to substantially thesame as the width of each conductive plug 16. For example, if a 0.35-μmrule is applied as a design rule of the semiconductor device, the widthof the frame member 44 is preferably set to about 0.45 μm. If a 0.18-μmrule is applied as a design rule, the width of the frame member 44 ispreferably set to about 0.25 μm. If a 0.09-μm rule is applied, the widthof the frame member 44 is preferably set to about 0.15 μm.

Additionally, it is preferable that an outline of the frame member 44 issubstantially equal to an outline of the upper conductive layer 18forming a bonding surface so that a lot of conductive plugs 16 can beformed inside the frame member 44.

In above-mentioned structure, the conductive plugs 16 and the insulatinglayer 20, which is made of an insulating material, provided between theconductive plugs 16 are surrounded by the frame member 44. Accordingly,even if a crack is generated in the insulating layer provided betweenthe conductive plugs 16, the crack cannot propagate outside the framemember 44 as shown in FIG. 11. It can be appreciated that thepropagation of the crack 30 is stopped by the frame member 44 in thestructure according to the present embodiment as shown in FIG. 11, whilethe crack 30 generated in the insulating layer 20 propagates inside thesemiconductor element in FIG. 3 which shows a conventional structure.

As mentioned above, according to the present embodiment, even if a crackis generated in an insulating layer inside a bonding pad by a mechanicalstress applied to the bonding pad when contacting a test probe pin orperforming wire-bonding, the crack does not propagate inside thesemiconductor element. Thus, generation of a moisture resistance defectdue to a water component entering inside the semiconductor element alongthe crack is. Additionally, since the insulating layer 20 in the bondingpad structure is not an island-like form but in an interconnected form,a portion of the insulating layer does not fall off.

Moreover, according to the present embodiment, the conductive plugs 16are not only surrounded by the frame member 44 but also completelysurrounded in vertical directions and horizontal directions togetherwith the insulating layer 20 by the lower wiring layer 14, theintermediate conductive layer 42, the upper conductive layer 18 and theframe member 44. Thus, even if a crack is generated, the crack cannotpropagate outside the bonding pad structure, which confines the crackwithin the bonding pad structure (inside the frame member).

It should be noted that the frame member 44 is formed of the sameconductive material as the conductive plugs 16 in the presentembodiment. Since the conductive material is, for example, a metal whichis softer than the insulating material forming the insulating layer 20,there are advantages in that it is suitable for a material to stoppropagation of a crack and the frame member 44 can be formed in the sameprocess as the process of forming the conductive plugs 16. However, itis not always necessary to form the frame member 44 by a conductivematerial, and the frame member 44 may be formed by a relatively flexibleinsulating material. As such an insulating material, there are, forexample, aluminum oxide (AlxOy), titanium aluminum nitride (TixAlyNz),etc.

In order to form the above-mentioned structure of the bonding pad,first, the conductive plugs 16 and the frame member 44 are formed on thelower wiring layer 14 so that the frame member 44 surrounds theconductive plugs 16, and, then, the insulating layer 20 is formed byfilling an insulating material between the conductive plugs 16, and,thereafter, the upper conductive layer 18 is formed on the conductiveplugs 16, the insulating layer 20 and the frame member 44. Thereby, thesurface of the upper conductive layer 18 can be made as a bondingsurface of the bonding pad.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

The present application is based on Japanese priority application No.2005-157538 filed May 30, 2005, the entire contents of which are herebyincorporated herein by reference.

1. A manufacturing method of a semiconductor element having an electrodeon a surface thereof, the manufacturing method comprising: forming aplurality of pole-like members and a frame member on a wiring layerinside the semiconductor element so that the frame member surrounds theplurality of pole-like members; forming an insulating layer by fillingan insulating material between the pole-like members; and forming aconductive layer on said plurality of pole-like members, said insulatingmember and said frame member so as to make a surface of the conductivelayer as a surface of said electrode.
 2. The manufacturing method asclaimed in claim 1, wherein said frame member is formed by the samematerial as said pole-like members.